Users have become increasingly reliant upon electronic systems to perform critical functions. Some electronic systems must be operative at all times. Telecommunication switches, for instance, route tens of thousands of calls per second. The failure of such systems, due to either equipment breakdown or loss of power, is unacceptable since it would result in the loss of millions of telephone calls and the severe disruption of commerce.
A number of factors may affect operational availability of a particular electronic system. Electronic systems are inherently susceptible to damage from voltage transients. A single-point ground system, commonly used in the United States, connects all equipment frames and a point in the return of the current carrying path in a particular electronic system to a single ground window. By providing a path directly to ground, the single-point ground protects the electronic system from transient voltages.
In addition to grounding protection, critical electronic systems typically rely on battery plants or other types of power plants to maintain a high level of operational availability. Battery plants use backup batteries to provide power, allowing the electronic systems to function even when commercial power is unavailable. Batteries in a battery plant may store a substantial amount of energy. Although necessary to allow the electronic systems to operate during a commercial power outage that may last for many hours, the substantial energy stored may become a liability under certain fault conditions. A fault occurring either in the electronic system, the power plant or a power distribution system may release some of the stored energy in the form of voltage or current transients. The transients may then travel through the single-point ground, causing considerable damage to other parts of the electronic system.
Accordingly, what is needed in the art is an apparatus and method for suppressing transient voltages caused by, for instance, faults in the electronic system or in the power distribution system.